The Wall Street Journal alleges this week that the US has ramped-up its number of spy drone missions over the Bushehr nuclear reactor ever since fuel rods were unexpectedly discharged from the facility in October, just two months after the facility became fully operational.

The US has long voiced concern over the possible procurement of a nuclear warhead by Iranians, but surveillance has increased significantly in the weeks following the recent discovery of spent fuel rods, US officials confirm on condition of anonymity.

According to unnamed sources speaking with the paper, the Iranian government was caught moving fuel rods from the Bushehr reactor to a cooling pond during the week beginning October 22. By November 7, an independent report completed by inspectors with the International Atomic Energy Agency (IAEA) confirmed the discovery.

During the weeks prior, the Journal reports, the US increased its number of surveillance missions using state-of-the-art unmanned aerial vehicles capable of capturing multiple forms of media from thousands of feet from the ground. In a November 19 letter sent from Tehran and made available to the Journal, Iranian leaders appealed to the United Nations to complain about the skyrocketing surveillance. Amid the rumored increase in US spying, though, an American drone caught flying near Bushehr was tailed by a fleet of Iranian fighter jets who attempted to take down the crafts.

Only eleven months earlier, a spy drone operated by the US was allegedly intercepted by Iran in mid-air and grounded, only for engineers there to allegedly dismantle and reverse engineer the UAV. Upon initial reports of the downed drone, a CIA official speaking anonymously to the Los Angeles Times said the aircraft can conduct photographic and video surveillance from the air, monitor cell phone conversations and can sniff out chemicals, all while remaining undetected in the air.

"It's bad — they'll have everything,” one official speaking on condition of anonymity told the Times.

On Friday, the US Senate passed an amendment to next year’s defense spending bill that will introduce a third round of harsh sanctions against Iran in hopes of dismantling any nuke procurement plans. According to a separate report published in the Journal, that measure will make it harder for Iran to receive precious metals, graphite, aluminum and steel, metallugrical coal and software for integrating industrial processes.